sizing T5 fixtures

[DelawareJim]

Hello all;

I've decided to take the plunge and get some HO T5 fixtures like the TEK or New Wave for growing in my basement. I currently have a grow chamber I built that is 52 inches wide by 24 inches deep and has 2 shelves 26 inches apart.

I also built some 2x4 shelves about the same dimensions for growing winter greens and my ever expanding collection of orchids and houseplants. All are running on T12 shop lights.

I see most people seem to be going with 4-tube fixtures while some people like Ross are going with either 4-tube or 8-tube fixtures. I'm thinking of going with 6-tube fixtures as a compromise.

Knowing for the most part the fixture size depends on available space (11, 15, or 19 inches wide), 8-tube fixtures would fit, but I'm concerned about leaf burn and of course cost. But on the flip side, I don't want to save some money now by getting the 6's and wish I'd gotten the 8's later, or find out I overspent and the 4's would work just fine.

Any advice from those who have been running these for a while would be appreciated.

Cheers.
Jim

[Ross]

The size doesn't matter except for the output. I think the 4-tube fixtures fit most folks setups, but if 6-tube fits yours, then that is best. Plants need to be pretty much under the tubes as fall-off of light gets pretty dramatic when off to the sides or ends of the tubes. I recommend the fixture you purchase be the one that does the best job of lighting the area you have to light. Leaf burn shouldn't be an issue because you can start with the light fixture too high and slowly lower closer to the leaves over a couple months. The fixture is the most expensive, so two will cost disproportionally more than one that covers same area. This is a one-time purchase, so choose wisely. Low-light plants can always be set off to side or further away.

[DelawareJim]

Ross;

Thanks for the info. I guess this just reinforces the general rule of thumb in hobbies, as with aquariums and ponds, to get the biggest you can fit and can afford.

I just need to get over the sticker shock of spending $500 for a fixture, tubes, and shipping.

Cheers.
Jim

[DelawareJim]

I've decide to go with the New Wave 4 foot by 8 bulb configuration at 40,000 lumens.

Now I need to figure spacing of the shelves with these lights.

Generally how far below the HO T5 lights can I keep the plants?

If I build the whole set up about 5 to 5 1/2 feet tall with a top to hang the upper most light fixture, middle shelf or shelves with fixtures hanging under them, and bottom shelf, how far apart should I build the shelves?

Am I limited to 2 fixtures and 2 plant shelves or can I get away with 3 fixtures and 3 plant shelves?

I currently have a shelf set up using T12 shop lights I use for starting seeds, It has 2 4 foot lights for each plant shelf:

The shelves are 25 inches apart and the bulbs are 12 inches above the shelves in this unit.

Thanks.

Cheers.
Jim

[Ross]

If it's any help, I grow lettuce, spinach and radish under my 8-tube fixture which sits about 12" above the plants. They covet full sun and as I recall I measured over 3500 foot-candles at 12" (something like that.) I feel strongly there are few orchids that would want that high a light for 10-12 hours so feel free to move lights higher still (or drop the shelves). I'd bet 18" will do just fine for most Phals, Paphs, Masdies and most Angraecoids. A good light meter will help.

[DelawareJim]

Originally Posted by Ross

A good light meter will help.

I currently use a Milwakee Instruments SM700 Lux meter that I got for my planted aquariums.

Milwaukee Instruments

Generally, I like it, but taking notes and then converting from Lux to footcandles gets tedious at times. I guess for hobby purposes though estimating 10 Lux = 1 FC is close enough.

Cheers.
Jim